This application is based on Japanese Patent Application No. 11-58592, filed Mar. 5, 1999, the contents of which are incorporated herein by reference. The present invention relates to a cryptographic communication terminal, cryptographic communication center apparatus, cryptographic communication system, and storage medium and, more particularly, to a cryptographic communication terminal, cryptographic communication center apparatus, cryptographic communication system, and storage medium which are characterized in that a plurality of cryptographic algorithms can be used and a new cryptographic algorithm can be safely and efficiently registered and used.
Various current devices connected to a network incorporate encryption techniques to prevent breaches of security. With the use of the these incorporated encryption techniques, electronic business transactions, contents distribution businesses, and the like using networks as media are growing. These businesses depend on the safety of the incorporated encryption techniques. Under the circumstances, studies on the design of safe, efficient cryptographic algorithms have been enthusiastically conducted.
According to a conventional system incorporating an encryption technique, once system specifications are determined by standardization or the like, a cryptographic scheme that can be used by the system is fixed. Consequently, the security level of the system is also fixed.
On the other hand, studies on cryptanalysis of cryptographic algorithms have also been enthusiastically conducted to evaluate the safety of the cryptographic algorithms concurrently with the studies on the design of safe cryptographic algorithms. Therefore, the cryptographic scheme used by a given system may be actually broken.
If the cryptographic scheme used by the system is broken in this manner, the system cannot be used unless the cryptographic scheme is updated. That is, in order to continue safe network communication, the cryptographic scheme of the system must be updated.
In updating the cryptographic scheme through the network, however, a problem is posed in terms of safety. For example, confidential information may leak to the outside. If the cryptographic scheme is to be updated without the mediacy of a network, updating must be performed in all the devices in the system one by one. This makes it impossible to efficiently update the scheme.